1. Field of the Invention
The invention relates to textile spindle
2. Description of Related Art
Textile spindles, which can compensate unbalance by approximating the actual main massinertia axis to the axis of rotation of a spindle mounting over two degress of freedom of the spindle shaft, are already known from EP-A1-0,209,799. In this known textile spindle, the spindle shaft, the shank of which is supported rotatably in a spindle-bearing housing via a neck bearing and a step bearing, is capable of executing a wobbling movement about the neck bearing, counter to the effect of a damping device arranged within the spindle-bearing housing. The spindle-bearing housing is itself connected at a distance from the spindle rail,E via a mounting sleeve, to the first ends of axis-parallel flexural-spring bars which are arranged distributed over the circumference of the mounting sleeve and the opposite ends of which are anchored to the spindle rail via a further mounting sleeve. A better engaging wharve is arranged on the spindle shaft in the region of the neck bearing.
Consequently, the spindle shaft, together with the upper part carrying the yarn bobbin, can tilt about the neck bearing to the extent of the wobbling capacity counter to the effect of the damping device. The mutually parallel flexural-spring bars of equal length form, together with the mounting sleeve, a three-dimensional parallelogram-like connection, the imaginary pairs of joints of which lie respectively in one of two radial planes which are spaced axially from one another and which extend parallel to the spindle rail. The spindle-bearing housing can therefore, in practice, move only with the effect of a parallel displacement in the radial direction, counter to the spring tension of the flexural-spring bars. Since a belt pulling force is exerted in the region of the neck bearing as a result of the wharve arrangement, inclination of the spindle shaft or of its bobbin-carrying upper part is thus prevented. The spindle-bearing housing executes the radial movements at right angles to the spindle rail.
To compensate unbalance during the rotation of the spindle, the spindle-bearing housing, in the position displaced parallel out of the neutral position, executes, together with the associated mounting sleeve, a translational oscillating rotational movement. The spindle-bearing housing alone already constitutes a relatively large mass. In the supercritical rotational-speed range, the mass inertia impedes dynamic movability in the radial direction of the spindle shaft increasingly with an increasing rotational speed. This is accompanied by an increase in undesirable bearing reaction forces between the spindle shaft and the neck bearing and step bearing. This leads to a premature wear of said bearings.
If, despite the described stiffening effect of the mass involved, the dynamic radial flexibility of the spindle shaft (which is desirable to compensate for unbalance), is to be preserved, this mass must be compensated by for reduced spring rigidity of the flexural-spring bars, each simulating a double joint. In order to withstand the corresponding material loads as a result of alternating bend stresses or to avoid premature fatigue fractures of the flexural-spring bars, stringent requirements are placed on their design with regard to material and surface quality. It is evident that these requirements can be satisfied only at a corresponding cost outlay. In a considerable number of instances, the use of such textile spindles is there for impossible for reasons of cost.